DESCRIPTION: (Applicant's Abstract) This Mentored Clinical Scientist Development Award (MCSDA) application details a program of research having the overarching goal of elucidating the behavioral component of liability to early-age onset drug use and the factors contributing to changes in liability during pubertal development. The career development and research plans are designed to provide the applicant with the necessary expertise to conduct multidisciplinary longitudinal research directed at delineating the interrelations among biological/behavioral and psychosocial factors underlying the liability to substance abuse. The term liability was first proposed by Falconer (1965) to reflect a normally distributed latent trait encompassing the variables contributing to the risk for adverse outcome. This proposal is directed at elucidating the behavioral component of liability and to determine how pubertal development and environmental factors interact with liability to influence substance use outcome. Only a few studies have attempted to clarify conjointly the contributions of biological, behavioral and environmental factors within a developmental framework. Virtually no research has addressed the impact of significant biological events, particularly pubertal status and timing and rate of pubertal development on liability for substance use and abuse. This investigation will enable the applicant to acquire the knowledge and skills to undertake multidisciplinary research into substance abuse etiology within the highly supportive research environment at the NIDA funded Center for Education and Drug Abuse Research.